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Water testing & Pasteurization in Africa
A guide to water testing in developing countries using a Portable Microbiology Laboratory, and how to pasteurize contaminated water using sunshine and a simple solar cooker.
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Water - Safe to Drink? Nepal

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Mwamongu Village water source, Tanzania

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Water source in Dar es Salaam, Tanzania

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The presence of the bacterium Escherichia coli indicates recent fecal contamination of water.

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Water tests should provide this information

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Components of the Portable Microbiology Laboratory with Colilert and Petrifilm tests for E. coli

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Old, inexact methods on the left, to be replaced by modern tests for E. coli, right

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Portable Microbiology Lab with materials for 25 Colilert & Petrifilm tests

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Prof. Metcalf holds the two Portable Microbiology Laboratory tests: Colilert MPN tube, and E. coli count Petrifilm.

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Colilert: A presence/absence test for E. coli in bottles or tubes

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Colilert for 100 ml, left, and 10 ml, tubes on right.

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Colilert is an approved water testing method in 40 countries

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ONPG and MUG are the two substates for E. coli in Colilert

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How to use Colilert MPN. Collect water in sterile WhirlPak (open well in Temeke Municipality, Dar es Salaam, Tanzania)

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Carefully remove cap from Colilert tube

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Use sterile pipette to add 10 ml of water source

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Carefully replace cap

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Shake tube to dissolve chemicals

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Incubate tubes at 35°C for next day results

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Tubes can also be incubated next to one's body to obtain next day results.

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Body incubation of Colilert tubes

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Next day Rresults Clear = no coliform bacteria. Yellow (ONPG+) = coliform bacteria present, possibly E. coli

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Use a battery-operated long UV light to shine on tubes. Blue fluorescence = MUG +, E. coli is present, water not safe to drink.

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The best test for E. coli in foods: E. coli Count Petrifilm

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Two substrates in Petrifilm for E. coli, lactose and BCIG

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To use Petrifilm, label sample source and time

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Use sterile pipette to collect exactly 1 ml of water

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Raise the edge of film to expose nutrient circle

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Add 1 ml of water sample to nutrient circle

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Carefully roll down film onto nutrient circle

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Use flat side of plastic spreader to gently distribute 1 ml over entire circle

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Petrifilms ready for incubation

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Petriflms covered with firm cardboard enables incubation on one's body, ~20 doublings for invisible bacteria to develop into visible colonies

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Results usually in 10-18 hr. E. coli = blue colonies with gas. Coliforms besides E. coli = red with gas.

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Petrifilm & Colilert tests correlate with risk of disease, WHO Guidelines for Drinking Water Quality, 2nd Edition.

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UN Habitat Water Testing Booklet, November, 2010

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Ready to start workshop. Boniphace translates for Prof. Metcalf

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Two water sources in Saka Saka. From a pump (green bucket) and an open stream (yellow bucket).

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Adults will sample either pump or stream water

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Mixing inoculated Colilert tubes, to incubate overnight

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Petrifilms also inoculated by either pump or stream water

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Next day demonstration of solar cooking, solar water pasteurization

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Next day results: Pump water yellow, MUG -, no E. coli. Stream yellow and MUG+, E. coli present.

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Examining Petrifilms the next morning

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Next day Petrifilm results are clear.

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Stream water (front) with ~100 E. coli colonies on each Petrifilm, very high disease risk. Pump water with coliform bacteria, but not E. coli, low disease risk.

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All villagers see results of grossly contaminated stream water, no E. coli contamination of pump water.

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Solar cooked rice in 2 hr

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Providing a year's supply of water testing materials to Saka Saka health workers

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Solar water pasteurization and cooking demonstrated in Saka Saka. This could be replicated in villages worldwide.

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Water testing/solar pasteurization workshop for Village Chiefs and Village Health workers, Meatu District, Tanzania, 2001

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Village health workers examine results the following day

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Village chief knows that MUG+ Colilert means that E. coli was in the town's river water source, unsafe water

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Health worker finds >10 E. coli on Petrifilm, town river source poses a very high risk of disease

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Boniphace explaining Petrifilm results of village water sources Meatu

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Workshop participants given Colilert tubes to test home water sources, Nyakach, Kenya, 2003

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Colilert tubes incubated overnight in Nyakach

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All home water sources ONPG +, contain coliform bacteria

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All water sources from shallow wells also contain E. coli

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Collecting Nyakach shallow well water for testing

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Results of Nyakach shallow well - > 10 E. coli/ml very high risk of disease

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Students at California State University, Sacramento, who contributed to water pasteurization work

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Water Pasteurization article, 1984

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Water Pasteurization Indicator (WAPI). When water reaches 65°C (149°F), wax melts and falls to the bottom. Water is pasteurized.

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Use a Cookit solar cooker. 5 liters pasteurized in 3 hours of sunshine

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Article on Cookit and WAPI to pasteurize water, 1999

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Water vendor collecting river water,  Mwanhuzi town, Meatu District, Tanzania, 2000

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Water vendors try to sell water in Mwanhuzi

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Guest House (hotel)

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River water provided for guests

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After testing river water, collect for solar pasteurization

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Heating river water in Cookit

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Temperature >60°C in 2 hours

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WAPI wax melted, water is pasteurized

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Ready to test pasteurized water

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Micro tests before (top) and after solar pasteurization

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Solar cooking & solar water pasteurization in Nyakach, Kenya

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Solar cook in Nyakach with WAPI

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Africa Women and Water Conference, Nairobi, July, 2008

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Water testing session

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Inoculating Petrifilms and Colilert tubes with water from their home areas

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Next day results of Nigeria water

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Examining Petrifilm results

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Prof. Metcalf shows 2004 Nobel Peace Prize winner Prof. Wangari Maathai Colilert test results

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And Petrifilm results

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In Bondo, Kenya, With Laban Onongno, UN-Habitat Chief Technical Advisor, Lake Victoria Wat/San Program

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Prof. Metcalf leads workshop for Bondo community, December, 2008

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Inoculating Colilert test with 10 ml of Bondo drinking water source

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Petrifilm test of Bondo drinking water source

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Next day results in Bondo

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Now we're microbiologists!

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Results from nine Bondo water drinking water sources

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PML methods taught in Bondo by Gobei Secondary School teacher Tobias Amolo, July, 2009

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Prof. Metcalf presents PML materials to Mr. Amolo, July, 2009

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Class results of local water sources before and after WaterGuard treatment.

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Test results before and after chlorination of water source

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UN-Habitat workshop in Kisumu, Kenya, July, 2010

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UN-Habitat water testing workshop, Harar, Ethiopia, November, 2010

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Harar certificate

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World Water Week, Stockholm, Sweden, August 20-26, 2011

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UN-Habitat booth. Demonstrating water testing.

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Portable Microbiology Laboratory for World Vision, Ghana

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Prof. Metcalf and UN Habitat's Lars Stordal at Rwanda workshop location

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Each workshop participant received a mini-PML, materials for 10 water test, and a WAPI

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Integrated Health Program, Democratic Republic of the Congo

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Workshop participants, Lodja, DRC

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Second day results

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Demonstrating solar water pasteurization

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With Dinah Chienjo (left)and Faustine Odaba at IWA Development Congress, Kenya, 2013

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International Water and Health Alliances booth

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Delegate inoculates Colilert. Water testing made easy with the PML.

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International Water and Health Alliances booth in Jordan

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American Society for Microbiology workshop, New Orleans

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American Society for Microbiology workshop participants

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